Mint plant named ‘Chelan Mint’

ABSTRACT

Mint selection 08-6-10, denominated ‘Chelan Mint,’ is a new  Mentha piperita  cultivar that produces a unique essential oil, a compact plant type and resistance to mint rust ( Puccinia menthae ) and mint wilt ( Verticillium dahlia ).

Latin name of the genus and species: Mentha piperita.

Variety denomination: ‘CHELAN MINT’.

FEDERAL SPONSORSHIP

None

TYPE OF PLANT AND NAME OF VARIETY

The present invention relates to a new and distinct variety ofpeppermint plant developed from a parent of the species Mentha piperitaL. The new variety will be identified as ‘Chelan Mint.’

BACKGROUND OF INVENTION

This plant was selected from a population of mint seedlings in researchplots on land near Monmouth, Oreg. and initially identified as 08-6-10.‘Chelan Mint’ originated as a seedling from an open pollinated polyploid‘Black Mitcham’ parent identified as 05-4-9. Diploid ‘Black Mitcham’peppermint is sterile and only becomes fertile in the polyploidy state.The fertile ‘Black Mitcham’ parent (05-4-9) to ‘Chelan Mint’ was one ofseveral mint lines in a polycross breeding system composed of selectedmale and female fertile genotypes.

DISCOVERY AND ASEXUAL REPRODUCTION

The primary objective in this breeding program was to develop a Mitchamtype peppermint variety having a specific oil composition, acceptableyield and resistant to mint wilt and mint rust. Mint wilt is caused by asoil-borne fungus, Verticillium dahliae, and mint rust is a leafinfection caused by the air-borne fungus Puccinia menthae. Onlyseedlings that showed no symptoms of mint wilt or rust were selected forfurther evaluation. ‘Chelan Mint’ was vegetative propagated by tipcuttings to increase the selection to 20 plants for continued evaluationin 2009. The selection was again vegetative propagated by stolonsections to over 300 plants for planting and evaluation in 2010. Whencompared to ‘Black Mitcham’ as a control, ‘Chelan Mint’ had less (or no)symptoms of mint wilt than the control and had no mint rust infection.Yield of ‘Chelan Mint’ is equivalent to ‘Black Mitcham’ in test plots asa single plant and in larger plot evaluations from 2009 to 2010.

‘Chelan Mint’ is asexually propagated to maintain the cultivar's geneticintegrity and as a means of increasing the selection for commercialplanting. Asexual propagation, by tip cuttings or stolon sections, is acommon practice in commercial mint cultivation and serves as a means ofpropagating the normally sterile mint plant. The inventor has conductedasexual propagation of ‘Chelan Mint’ for greenhouse and field plantingin Monmouth, Oreg., each year since 2008 and the genotype comes true toform with each generation.

SUMMARY OF THE INVENTION

Mint selection 08-6-10, denominated ‘Chelan Mint,’ is a new Menthapiperita cultivar that produces an essential oil different incomposition than commercially grown mint varieties. The essential oil issimilar to standard peppermint mint oil in component composition butdiffers in the typical ratio of components. Organoleptically it differsfrom typical peppermint oil. It is resistant to mint rust and moreresistant to Verticillium mint wilt than current commercially grownvarieties.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying color figures show the typical one year old greenhousevegetative growth of ‘Chelan Mint’ and depicts the color as nearly asreasonably possible.

FIG. 1 illustrates the growth and branching pattern of the new mintplant.

FIG. 2 illustrates the shape of the leaf and flower on a terminalflowering shoot.

DESCRIPTION OF PLANT

My new mint plant improves upon and is distinct from other mint plantsin several characteristics, including but not limited to, the following:

-   -   1. The ability to produce an essential oil different in        composition but with similar components as ‘Black Mitcham’        peppermint;    -   2. A more compact plant but with a branching pattern similar to        its parent;    -   3. An early spring growth for a potential double harvest in one        growing season;    -   4. A level of resistance to mint wilt (Verticillium dahliae)        equal to or greater than that of its parent and the commercially        grown ‘Black Mitcham’ peppermint.    -   5. Resistance to mint rust caused by Puccinia menthae.

The essential oil extracted from ‘Chelan Mint’ has the same componentsas that of commercial oil produced by ‘Black Mitcham’ peppermint asillustrated in Table 1. However, the ratio of oil components differs inthe commercial peppermint oil and that of ‘Chelan Mint.’ Theconcentration of menthone in the oil of ‘Chelan Mint’ is lower than thatof ‘Black Mitcham.’ The amount of Menthofuran and Menthyl Acetate in theoil of ‘Chelan Mint’ is higher than that of ‘Black Mitcham.’ The mentholhas a similar concentration as that of ‘Black Mitcham.’ Organolepticallythe oil of ‘Chelan Mint’ is different than that of ‘Black Mitcham,’reflecting the difference in oil component ratios.

TABLE 1 Composition of ‘Chelan Mint’ Oil from Test Plots Compared tocommercial ‘Black Mitcham’ Peppermint Oil and Oil from ‘Black Mitcham’Peppermint Grown in Test Plots located near Monmouth, Oregon. Commercial2008 Test Plot 2008 Test Plot Essential Oil ‘Black ‘Black ‘ChelanComponents Mitcham’ 1/ Mitcham’ 2/ Mint’ 3/ α-pinene 0.82 0.80 <1.00β-pinene 1.06 1.03 <1.00 l-limonene 1.78 1.73 1.40 1,8-cineole 5.33 4.904.20 l-menthone 20.00 19.43 10.00 Menthofuran 4.35 4.23 20.70Iso-menthone 3.19 3.14 1.30 l-menthyl acetate 5.09 5.36 7.80 Neo-menthol5.40 5.52 4.00 B-caryophyllene 0.83 0.85 1.60 l-menthol 45.20 44.6044.20 Pulegone 2.17 2.14 <1.00 Germacrene-D 1.22 1.37 <1.00 The numberslisted in the above table are percentages based upon the analysis of therespective mint oils by gas chromatography. The percentages aredetermined by calculation of the relative peak areas. 1/ Commercial oilsample typical of what is produced by peppermint producers. 2/ ‘BlackMitcham’ oil from a control plant in the 2008 seedling test plot. 3/‘Chelan Mint’ oil from a single plant harvest from the 2008 test plots.

TAXONOMIC DESCRIPTION OF ‘CHELAN MINT’

This new plant, under greenhouse and field growing conditions, is a bushtype plant with lateral branches at each node of the main stems. Theaverage growth of ‘Chelan Mint’ in height is 50 cm and width is 25 cmbut will vary based on fertilizer, soil quality, and water application,amongst other known factors that affect growth patterns. The main stemcan grow to 70 cm in height. Secondary and tertiary branching occurs toform a compact growth habit. When ‘Chelan Mint’ is mature and ready forharvest, the main stem at mid-plant (approximately between the eleventhand twelfth node) is 3.3-3.9 mm in width. The secondary and tertiarybranch stems are 2.2-2.7 mm and 1.5-2.0 mm in width, respectively. Theaverage length of secondary branches is 12 cm. The tertiary branches,when present, are up to 6 cm in length. The stems are square, glabrous,and a green color illustrated by The Fifth Edition Royal HorticulturalSociety Colour Chart 143B green group, and has spots, randomly spaced,of anthocyanin pigment.

Mature leaves at the bottom of the plant are ovate to lanceolate as areleaves on secondary branch stems. Leaves on upper mature plants, bothmain and secondary stems are more lanceolate (FIG. 2). The adaxial leafsurface is glabrous. The abaxial leaf surface is sub-glabrous with oilglands distributed across the surface. Mid-main stem leaf size atflowering is 24-30 mm in width and 55-65 mm in length. Leaf size onsecondary branches at flowering is 15-18 mm in width and 27-32 mm inlength. Leaf petioles on the main stem leaves are 11-15 mm in lengthwhile petioles on secondary branch stem leaves are 4-6 mm in length.Leaves on the mid-main stem and lower tend to be slightly lobed anddenticulate while the leaves on the upper plant tend to be more dentate.The main stem leaves have from 9 to 12 teeth on each side. The adaxialleaf surface is dark green in color, ranging from Fifth Edition RoyalHorticultural Society Colour Chart N137B to N137C in the green groupclassification. The abaxial leaf surface is a green color as illustratedby Fifth Edition Royal Horticultural Society Colour Chart 146A, yellowgreen group. The leaf has 6-9 lateral veins, more or less in paralleloff the main vain that runs from the petiole to the tip of the leaf. Theveins are prominent in all leaves of ‘Chelan Mint.’

The inflorescence is an inconspicuous raceme with capitate flowersdeveloping at the last few nodes of the stem. The raceme varies inlength from 7 to 10 cm and is influenced by environmental factors. Thecapitate flowers are 15-20 mm in width and 10-15 mm in length. Theflowers consist of five petals fused into a two lipped corolla. Thecorolla is light in color ranging from Fifth Edition Royal HorticulturalSociety Colour Chart 84D in the Violet Group, to white in the FifthEdition Royal Horticultural Society Colour Chart N155B white group. TheCalyx is generally green and is 143B to 143C in the Fifth Edition RoyalHorticultural Society Colour Chart, Green Group. The gynoecium consistsof a single pistil with two lobed stigma that is exserted. Theandroecium consists of four stamens, each with a distinct filament andanther.

While the plant that comprises the present invention has been describedin connection with a specific embodiment thereof, it will be understoodthat this application is intended to cover any variation, uses, oradaptation of the invention (particular those induced by cultivationunder different environmental conditions) following, in general, theprinciples of the invention and including such departures from thepresent disclosure as come within known or customary practice in the artto which the invention pertains and as may be applied to the essentialfeatures hereinbefore set forth, and as fall within the scope of theinvention and the limits of the appended claim.

I claim:
 1. A new and distinct variety of peppermint plant, substantially as shown and described, characterized particularly by improving resistance to mint rust, and producing a unique essential oil. 